1. Field of the Invention
The present invention relates to a screw, in particular, a high-speed fastening screw.
2. Description of the Related Art
Referring to FIG. 1, a conventional screw 1 comprises a screw head 10, a shank 11 extending from the head 10 along a shank axis “θ”, a drilling portion 13 disposed at the distal end of the shank 11, and a plurality of threads 12 disposed on the shank 11; wherein each of the threads 12 provides with a notch 121 disposed around the outer edge thereof, and a plurality of the notches 121 are assumed to be sequentially joined by an imaginary line “a”, started from an initial notch “c” located adjacent to the drilling portion 13 to a final notch “d” located adjacent to the screw head 10, which results in the line “a” being inclined with respect to the shank axis “θ” by an angle “ρ”.
While screwing, the screw 1 is initially drilled into the object through the drilling portion 13 and the threads 12, and further the notches 121 assist to cut the fibers and receive the debris (not shown in the figures). By means of the inclination of the imaginary line “a” and the smaller angle “ρ” in FIG. 1, the notches 121 solely spread around part of the shank 11 (shown in end view of FIG. 2) and can not thoroughly cut off the fibers of the object. Thereafter, the unsevered fibers would be facilely twisted round the shank 11, which increases the screwing resistance and affects the screwing efficiency.
To solve the aforementioned problems, some manufacturers may intend to dispose a plurality of notches 221 on each of the threads 22, as shown in FIG. 3. However, the more notches 221 are on the threads 22, the less dimension of each notch 221 is. The notches 221 with smaller dimensions would not substantially cut and sever the fibers, which causes fibers to be twisted round the shank and accumulated within the object and furthers the object easily to be destroyed. In addition, the configuration of multiple notches 221 on the threads 22 may also cause injuries to the operators while screwing. Thus, screw 1 and 2 still requires further improvements.